I don't know how to do it but I've had it checked at my last few appointments and all they do is reach up and feel the cervix to see if it's open. I think you have to know what a closed cervix feels like before you could tell what an open cervix feels like, and I have no idea. Then you have to know how many centimeters it is open...?... It's not the most comfortable but it doesn't hurt any worse than doing the deed, but there is a lot of pressure. At this point in my pregnancy I know I couldn't reach up there, LOL.